1. Field of the Invention
The invention relates to a continuous method for treating an article having a textile surface , such as a broadloom carpet or carpet tiles, with a stainblocker composition to impart stain resistance thereto, and to the article produced thereby.
2. Description of the Prior Art
In the industrial production of articles having a textile surface thereon, such as a broadloom carpet or carpet tiles, it is common to treat such articles with a composition to impart added desirable properties thereto, such as resistance to staining by a variety of agents, e.g. foods or beverages. Some especially troublesome stains are coffee, black tea and red wine.
In the industrial production of such articles it is also common to use differentially dyeable nylon yarns. By the term xe2x80x9cdifferentially dyeablexe2x80x9d it is meant that the article contains yarns having at least two different dyeabilities, such as acid dyeable yarn and cationic (xe2x80x9ccatxe2x80x9d) dyeable yarn. Often a desired aesthetic effect in a carpet is possible only by combining yarns of these two different dyeabilities. Both dyeabilities are available in various dye depths, such as light, regular, deep and extra deep acid dye and light and regular cat dye.
Compositions referred to as xe2x80x9cstainblockersxe2x80x9d are commonly applied to non-differentially dyeable carpets or carpet tiles to impart stain resistance.
There is presently available both a continuous process and a discontinuous, or batch-wise, process for applying a stainblocker composition to a carpet made of non-differentially dyeable yarns.
Continuous Conventional Process The steps of a conventional process for applying a stainblocker composition to a textile surface (such as a broadloom carpet) made of non-differentially dyeable yarns are listed along the left hand side in FIG. 3. In the conventional continuous process a running line of colored carpet (colored as by dyeing or printing), after rinsing and suction hydroextraction, is passed through an aqueous liquid treatment bath containing a stainblocker composition and a surfactant. The temperature of the bath is in the range from twenty to sixty degrees Celsius (20 to 60xc2x0C.). The residence time of the carpet in the bath is usually not adjusted as an independent critical parameter but is instead a function of the speed of the carpet line. After removal from the bath the carpet passes through a steam chamber wherein it is exposed to saturated steam for about sixty to ninety (60 to 90) seconds. Thereafter, conventional finishing steps for the carpet typically include: a suction hydroextraction operation where residual liquid is vacuumed from the carpet; a cold water rinse operation (either by spraying or passing the carpet through a dip trough); another suction hydroextraction operation; and a final drying.
Batch-wise Conventional Process The batch-wise process for applying the stainblocker composition and a surfactant to a textile surface made of non-differentially dyeable yarns (such as a broadloom carpet) is termed the xe2x80x9cwinch/beckxe2x80x9d process. In the batch-wise winch/beck process discrete dyed carpets are immersed in a vat having a bath including a stainblocker composition and a surfactant. The temperature of the bath in the batch-wise winch/beck process is slightly higher than in the continuous process, in the range from seventy to seventy-five degrees Celsius (70 to 75xc2x0C.), and the residence time in the bath is on the order of twenty minutes. After removal from the bath, the carpet is subjected to the conventional finishing steps such as rinsing with cold water in situ, or after unloading from the hot application bath, rinsed by spray bar followed by a vacuum extraction operation to ensure no residual stainblocker is left.
In both the continuous process and the batch-wise process the stainblocker composition is preferably of the anionic functionalized type, and more preferably, of the sulphone resole type having nonionic functionality.
Tile Production To produce carpet tiles treated with a stainblocker composition it is common practice first to treat a broadloom carpet with a stainblocker composition in one of the manners specified, and after a backing is applied, to cut the broadloom carpet into pieces of the desired size to form carpet tiles.
Stainblockers Suitable anionic functionalized type stainblocker compositions include sulphonated phenol formaldehyde condensate types, maleic acid anhydride types, acrylate dispersions and mixtures thereof. Anionic functionalized type stainblocker compositions should be present between three weight percent (3 wt %) and five weight percent (5 wt. %) based on the weight of the nylon carpet fiber. When anionic functionalized type stainblocker compositions are used, the pH of the bath must be adjusted to between 2 and 5.
Examples of commercially available anionic functionalized type stainblocker compositions are available from E. I. Du Pont de Nemours and Company, Wilmington, Del., under the trademarks SR 300, SR 400 and SR 500; from Du Pont de Nemours International S. A., Geneva, Switzerland, under the trademark NRD 334; from Allied Colloids, Bradford/West Yorkshire, U.K., under the trademark Alguard RD; and from Bayer AG, Leverkusen, Germany, under the trademark Baygard DT.
When sulphone resole type stainblocker compositions with nonionic functionality are used, they should be present at between four weight percent (4 wt. %) and six weight percent (6 wt. %) based on the weight of the nylon carpet fiber, and the pH must be adjusted to between 6 and 7.5. An example of a commercially available sulphone resole type stainblocker composition with nonionic functionality is available from E. I. Du Pont de Nemours and Company, Wilmington, Del. under the trademark Zelan 8236.
The pH of the treatment bath may be adjusted by known acid donor additives such as acetic acid, citric acid and sulfamic acid.
Surfactants A surfactant may be added to the stainblocker bath separately or may be included as part of the stainblocker composition. The surfactant may be anionic, amphoteric or nonionic in nature. Preferably, the surfactant used will be either an alkylated diphenyl oxide disulfonate sodium salt, alone or in combination with an alkylnaphtalene sulfonic acid formaldehyde condensate sodium salt. The surfactant is generally added to the bath at a rate of between one (1) and four (4) grams per liter. Suitable surfactants are available from E. I. Du Pont de Nemours and Company, Wilmington, Del. under the trademark Zelan 50; from Dow Chemical Company, Midland, Mich., under the trademark Dowfax 3B2; or from BASF AG, Ludwigshafen, Germany, under the trademark Primasol NF.
Problem With Conventional Methods for Differentially Dyeable Textile Surfaces Unfortunately, when either the continuous process or the batch-wise process is used to apply a stainblocker composition to a broadloom carpet containing differentially dyeable yarns the cationic dyestuff xe2x80x9cbleedsxe2x80x9d from the cat dyeable yarn into the surrounding stainblocker treatment bath, resulting in an unacceptable visual color change.
Low Liquor Method The only publicly known system to apply a stainblocker composition to a differentially dyeable carpet is a method known as the xe2x80x9clow liquorxe2x80x9d method. Using the xe2x80x9clow liquorxe2x80x9d method a differentially dyeable carpet may attain at least a modest degree of stain resistance. In the xe2x80x9clow liquorxe2x80x9d method a cold-foamed liquor including a stainblocker composition and a fluorocarbon material are co-applied topically to the carpet. Thereafter the carpet is dried, without steam or water rinse. In the past, the stainblocker composition typically utilized was the acrylate dispersion sold by 3M Corporation under the trademark xe2x80x9cFX-661xe2x80x9d, while the fluorocarbon material typically utilized was those sold by 3M Corporation under the trademarks xe2x80x9cFC-3611xe2x80x9d, xe2x80x9cFC-3602xe2x80x9d or xe2x80x9cFC-1395xe2x80x9d. However, the low liquor method is useful only with a carpet having a very low xe2x80x9cwet pick-upxe2x80x9d, on the order of fifteen to twenty percent (15-20%). Wet pick-up (wpu) is the ratio of the weight of the liquid picked-up by the carpet from a treatment bath to the weight of the carpet. Moreover, with the low liquor method, the stainblocker composition penetrates into only about the upper twenty-five percent (25%) of the height of the pile elements of a differentially dyeable carpet. This depth of stainblocker penetration is not believed to be sufficient to impart a high degree of stain resistance.
Accordingly, in view of the foregoing, it is believed advantageous to provide a process for treating an article having a textile surface containing differentially dyeable nylon yarns, such as a broadloom carpet or carpet tiles, to impart a high degree of stain resistance thereto, while maintaining good color stability.
In one a first aspect the present is a method of treating articles having a textile surface (such as broadloom carpets or carpet tiles) with a stainblocker composition to impart stain resistance thereto. The textile surface of the articles may be made of either differentially dyeable nylon yarns or acid-dyeable nylon yarns.
The textile surface of the article is colored with acid dyestuffs and cationic dyestuffs (in the case of an article made of differentially dyeable nylon yarns) or with acid dyestuffs (in the case of an article made of acid-dyeable nylon yarns). The coloring may be accomplished either by dyeing or by screen or spray printing. After coloring, this embodiment of the method comprises the sequential steps of:
(a) applying a stainblocker composition to the textile surface of the article, the stainblocker composition having a temperature from twenty to ninety-five degrees Celsius (20 to 95xc2x0 C.);
(b) drying the article in a drying zone having a temperature in the range from seventy-five degrees Celsius to ninety-five degrees Celsius (75-95xc2x0 C.) for a time sufficient to allow the stainblocker composition to react with the nylon yarn in the textile surface; and
(c) rinsing the textile surface of the article with water, and thereafter drying the same,
such that substantially the entire textile surface of the article is coated with a stainblocker composition whereby the textile surface has a stain resistance of 9 or higher on the AATCC Red 40 Stain Scale.
A broadloom carpet (with the backing thereon) may be cut into pieces to form carpet tiles either before or after it is colored, or after the final drying step.
When the article is in the form of carpet tiles, the tiles lay loosely upon and are conveyed by a transport belt through the stainblocker application. For carpet tiles the stainblocker composition is applied using a flood process by a flood applicator. Broadloom carpets may be transported by any suitable transport mechanism and the stainblocker composition can be applied by any appropriate application device.
Preferably, the drying zone of step c) uses infra-red energy to dry the textile article. Preferably, the temperature of the drying zone is in the range from eighty degrees Celsius to eighty-five degrees Celsius (80-85xc2x0 C.).
If the stainblocker composition is of the sulphone resole type having nonionic functionality (as is preferred) the stainblocker composition is present between one and one-half percent (1.5%) and six percent (6%), and more preferably, between two percent (2%) and three percent (3%) or between one and one-half percent (1.5%) and two (2%) percent, based on the weight of the nylon yarns. The pH of the stainblocker bath is between six (6) and seven and one-half (7.5). Alternatively, if the stainblocker composition is of the anionic functionalized type, such as that selected from the group consisting of sulphonated phenol formaldehyde condensate type, maleic acid anhydride type, acrylate dispersions and mixtures thereof, the stainblocker is present between one percent (1%) and five percent (5%) based on the weight of the nylon yarns; and the pH of the stainblocker bath is between two (2) and five (5).
In accordance with another aspect the invention is also directed to the article having a textile surface treated with the stainblocker composition in accordance with the method described herein.